Occurrence of hydrocarbon-degrading nitrogen-fixing bacteria in the rhizosphere of Paspalum vaginatum Sw.

Several nitrogen-fixing and hydrocarbon utilizing bacteria were isolated from the rhizosphere of the turf grass Paspalum vaginatum Sw. using four different hydrocarbons; crude oil, decane, diesel and engine oil as substrates. The isolates showed between 98%-99% 16S rRNA gene similarity with species of Alcaligenes, Brevundimonas and Klebsiella. Only Alcaligenes faecalis C1B, Klebsiella varicola C3B and Klebsiella varicola C3BB had the nifH gene; and the genes responsible for nitrogen-fixing abilities of all the isolates were not plasmid borne. Three of the isolates, Brevundimonas diminuta C4B, Alcaligenes faecalis B5 and Alcaligenes faecalis D4A with the ability to grow well in crude oil as carbon and energy source were selected for further studies. Alcaligenes faecalis B5 had the highest growth rate constant of 0.038 µ-1 with a mean generation time of 18.46 h. Analysis of culture extracts by gas chromatography with flame ionization detector showed that Alcaligenes faecalis B5 degraded 90.5% of crude oil in 24 days, while Alcaligenes faecalis D4A and Brevundimonas diminuta C4B biodegraded 84.6% and 82.1% of the oil respectively. Confirmation of nitrogen fixing ability was determined by the acetylene reduction assay (ARA). Alcaligenes faecalis B5 produced the highest amount of ethylene (15.18 nmol) after 24 h of incubation, while Alcaligenes faecalis D4A and Brevundimonas diminuta C4B produced 12.10 nmol and 9.60 nmol of ethylene respectively. Nitrogen-fixing hydrocarbon utilizers are therefore potential seeds in the bioaugmentation of nitrogen-limited hydrocarbon-polluted environments

Occurrence of hydrocarbon-degrading nitrogen-fixing bacteria in the rhizosphere of Paspalum vaginatum Sw.

Several nitrogen-fixing and hydrocarbon utilizing bacteria were isolated from the rhizosphere of the turf grass Paspalum vaginatum Sw. using four different hydrocarbons; crude oil, decane, diesel and engine oil as substrates. The isolates showed between 98%-99% 16S rRNA gene similarity with species of Alcaligenes, Brevundimonas and Klebsiella. Only Alcaligenes faecalis C1B, Klebsiella varicola C3B and Klebsiella varicola C3BB had the nifH gene; and the genes responsible for nitrogen-fixing abilities of all the isolates were not plasmid borne. Three of the isolates, Brevundimonas diminuta C4B, Alcaligenes faecalis B5 and Alcaligenes faecalis D4A with the ability to grow well in crude oil as carbon and energy source were selected for further studies. Alcaligenes faecalis B5 had the highest growth rate constant of 0.038 µ-1 with a mean generation time of 18.46 h. Analysis of culture extracts by gas chromatography with flame ionization detector showed that Alcaligenes faecalis B5 degraded 90.5% of crude oil in 24 days, while Alcaligenes faecalis D4A and Brevundimonas diminuta C4B biodegraded 84.6% and 82.1% of the oil respectively. Confirmation of nitrogen fixing ability was determined by the acetylene reduction assay (ARA). Alcaligenes faecalis B5 produced the highest amount of ethylene (15.18 nmol) after 24 h of incubation, while Alcaligenes faecalis D4A and Brevundimonas diminuta C4B produced 12.10 nmol and 9.60 nmol of ethylene respectively. Nitrogen-fixing hydrocarbon utilizers are therefore potential seeds in the bioaugmentation of nitrogen-limited hydrocarbon-polluted environments

Microbial assessment of the armpits of some selected university students in Lagos, Nigeria

A study of the carriage of microorganisms in armpits and prevailing factors was carried out on 80 students of the University of Lagos. The armpits were swabbed and the microbiological analyses were carried out on the swab samples. The organisms isolated include Staphylococcus epidermidis (35%), Staphylococcus aureus (3%), Staphylococcus cohnii (3%), Staphylococus haemolyticus (15%), Staphylococcus hominis (25%),Micrococcus luteus (9%), Staphylococcus capitis (6%), Staphylococcus saprophyticus (3%) and Candida tropicalis (1%). Questionnaires on gender and health related factors were administered to the subjects. Moststudents regardless of sex, used toilet soap (62.5%), had their bath twice daily (60%), used sponge for body scrubbing (87.5%) and shaved regularly (78.75%) but these did not have any significant influence on thecarriage of microorganisms (P = 0.05). More female participants used deodorants, than the males. The bacterial and fungal counts in the armpits of females were lower than the counts from male armpits, which means that the use of deodorant reduced the carriage of microorganisms. From the antibiotic sensitivity tests carried out on S. aureus, the highest sensitivity was recorded for Ofloxacin while the least was for  Cotrimoxazole. However the bacterium was resistant to most antibiotics tested. The DNA profile of S. aureus showed that none of the strains had a plasmid thereby suggesting that the antibiotic resistance genes in these strains could be chromosomally-encoded.Keywords: Microorganisms, armpit, university students, Lagos, Nigeria

Influence of pH, temperature and nutrient addition on the degradation of atrazine by Nocardioides spp. isolated from agricultural soil in Nigeria.

Aims: To effectively exploit the atrazine degrading capabilities of Nocardioides spp. isolated from agricultural soil samples in Nigeria and ascertain the effect of pH, temperature and nutrient addition on the degradation process. Methodology and results: Isolates were cultivated on atrazine mineral salts medium at a temperature range of 4 °C - 45 °C and a pH range of 3-10. An optimum atrazine degrading activity was observed in the isolates between temperatures of 25 °C and 37 °C and between pH 5 and 8. Different carbon sources (glycerine, glucose, chitin, cellulose and sodium citrate) and nitrogen sources (urea, biuret, cyanuric acid, potassium nitrate and ammonium chloride) were also added to the medium. The addition of carbon and nitrogen sources did not increase degradation rates although urea and glycerine repressed the degradation ability of the isolates. Statistical analyses of variance at P < 0.05 showed no significant differences in the growth and degradation rates by both bacterial isolates under these conditions. Conclusion, significance and impact study: Atrazine degradation by Nocardioides spp. is pH and temperature dependent, and requires no additional sources of carbon and nitrogen. Hence, its use in bioremediation of atrazine contaminated agricultural soil should be explored

Microbial assessment of the armpits of some selected university students in Lagos, Nigeria

A study of the carriage of microorganisms in armpits and prevailing factors was carried out on 80 students of the University of Lagos. The armpits were swabbed and the microbiological analyses were carried out on the swab samples. The organisms isolated include Staphylococcus epidermidis (35%), Staphylococcus aureus (3%), Staphylococcus cohnii (3%), Staphylococus haemolyticus (15%), Staphylococcus hominis (25%)

Microbial Quality of Public Swimming Pools in Lagos

The microbial quality of some public swimming pools in Lagos State, Nigeria was investigated to determine possible risks of infections to swimmers. Ten swimming pools (Pools AJ) were investigated for their microbial and physico-chemical qualities. The pH of the pools ranged from 5.24-8.71 and the residual chlorine ranged from 0.01-0.07. Water samples from the pools were cultured on differential and selective media. The microbial loads varied with different swimming pools. The fungal population ranged from 0-4.7× 10 4 cfu ml-1, while the bacterial population ranged from 0-1.12 x 10 5 cfu ml-1. Eight bacterial isolates were obtained and identified using Microbact 24E kit. Fungal isolates (6) were identified by microscopy, Gram’s staining and chloramphenicol test. The isolates include Aeromonas hydrophila (4), Burkolderia pseudomallei (2), Serratia marcescens (1), Enterobacter agglomerans (1), Candida albicans (3), Saccharomyces spp.(2) and Aspergillus flavus (1). Antifungal sensitivity test showed 50% susceptibility to nystatin and 50% resistance to voriconazole, while the bacteria were resistant to most of the antibiotic tested. The Multiple Antibiotics Resistance (MAR) index for the isolates ranged from 0.125 to 1.000. The feedback from the questionnaires administered, showed that unhygienic practices and maintenance of pools could contribute to low levels of swimming pool water quality. The high microbial loads and the types of microorganisms isolated from the pools show that contaminated swimming pools can constitute a serious public health hazard to the users

Metabolism of Atrazine in Liquid Cultures and Soil Microcosms by Nocardioides Strains Isolated from a Contaminated Nigerian Agricultural Soil

Atrazine-degrading microorganisms designated EAA-3 and EAA-4, belonging to the genus Nocardioides, were obtained from an agricultural soil in Nigeria. The degradation kinetics of the two strains revealed total disappearance of 25 mg l-1 of atrazine in less than 72 h of incubation at the rate of 0.42 mg l-1 h-1 and 0.35 mg l-1 h-1, respectively. Screening for atrazine catabolic genes in these organisms revealed the presence of trzN, atzB, and atzC. Other genes, specifically atzD, were not detected. Potential intermediates of atrazine catabolic route such as hydroxyatrazine, desethylatrazine, and desisopropylatrazine, and desisopropylatrazine were utilized as sources of carbon and energy, while desisoprophl desethyl-2-hydroxyatrazine and desisopropyl-2-hydroxyatrazine were attacked but in the presence of glucose. A soil microcosm study showed that degradation was faster in microcosms contaminated with 13 mg of atrazine per g-1 of soil compared with 480 mg g-1 of soil. In the former, degradation was 10% higher in the inoculated soil than the non-inoculated control (natural attenuation) over the 28-day study period. Corresponding value obtained for the latter was nearly 70 % higher. This study has demonstrated that the bacterial strains isolated enhanced atrazine degradation and the catabolic activities of these strains were not affected with increasing soil atrazine concentration

Degradation of aviation fuel by microorganisms isolated from tropical polluted soils

The degradation of aviation fuel was observed in soil samples from a polluted site at the aviation fuel depot, Lagos Airport, Nigeria. The percentage of occurrence of bacterial aviation fuel–utilizers were less than 1.0% of the heterotrophic populations, while the fungal-degraders were between 2.547-16.053%. There were no significant statistical differences for both the bacteria and fungi estimations among the soil samples. Enrichment of soil samples with aviation fuel resulted in the isolation of five bacteria (Pseudomonas aeruginosa, Micrococcus luteus, Corynebacterium sp., Flavobacterium rigense, Bacillus subtilis), three yeasts (Rhodotorula sp., Candida tropicalis, Saccharomyces sp.) and two molds (Aspergillus niger, Penicillium sp.). Utilization of the substrate by bacteria and yeast isolates resulted in an increase in population density and subsequent decrease in pH value and residual aviation fuel concentration. Over 90% of the n-alkane fraction of the aviation fuel supplied at 0.5% v v-1 concentration was degraded in 14 days by Pseudomonas aeruginosa, Micrococcus luteus and Corynebacterium sp. There were differential growth responses by the strains to dodecane, benzene, toluene and naphthalene, while growth was not supported by hexane and cyclohexane. Thus, enrichment with of soil contaminated with aviation fuel led to the isolation of competent hydrocarbon degraders

Establishment and characterization of atrazine degrading cultures from Nigerian agricultural soil using traditional and Bio-Sep bead enrichment techniques.

Traditional and in situ enrichment using porous Bio-Sep beads fortified with atrazine were used to obtain mixed consortia of atrazine-degrading bacteria. Cultures derived from both enrichment techniques showed rapid degradation of atrazine and the composition of consortia varied depending on enrichment type and atrazine concentration present in both the selective media and in atrazine fortified Bio-Sep beads as determined using denaturing gradient gel electrophoresis (DGGE). The DGGE analysis also revealed the presence of many bands corresponding to various bacteria both cultured and uncultured. All enrichment cultures possessed trzND genes. The atzBC genes were detected in all bead enrichments while only atzC was present in one soil enrichment. The atrazine chlorohydrolase gene (atzA) and cyanuric acid amidohydrolase genes (atzD) were not detected in any of the enrichment cultures. In soil samples, trzN and trzD were the only known atrazine catabolic genes detected. Parallel degradation studies with atrazine potential metabolites showed extensive loss of these compounds from the culture media. The results indicate that in situ enrichment with Bio-Sep beads might be a viable method to cultivate atrazine-degrading bacteria not currently represented in existing culture collections. The triazine chlorohydrolase encoded by trzN commonly found in most Gram-positive atrazine-degrading bacteria, was more prevalent than atzA. Thus, the detection of known atrazine-catabolic genes in soil or bacteria from tropical African contaminated systems is an indication of the likely global distribution of these important s-triazine genes

Effect of Corn Steep liquor on growth rate and Pyrene Degradation by Pseudomonas strain

The growth rates and pyrene degradation rates of Pseudomonas sp. LPl and Pseudomonas aeruginosa LP5 were increased in corn steep liquor (CSL) supplemented. On pyrene alone the higher specific growth rate of LPl was 0.818 h-1, while on CSL-supplemented pyrene MSM, the value was 0.026 h-1. For LP5 the highest growth rate on CSL-supplemented pyrene-MSM was 0.034 h-1. Conversely, on pyrene alone the highest rate was 0.024 h-1. CSL led to marked reduction in residual pyrene. In the case of Pseudomonas sp. LPl values of residual pyrene were 58.54 and 45.47 %, respectively, for the unsupplemented and supplanted both cultures, showing a difference of 13.09 %. For LP5 the corresponding values were 64.01 and 26.96 %, respectively, showing a difference of 37.05 %. The rate of pyrene utilization by LPl were 0.08 and 0.11 mg l-1 h-1 on unsupplemented and supplemented media, respectively. The corresponding values for LP5 were 0.07 and 0.015 mg l-1 h-1, respectively. These results suggest that CSL, a cheap and readily available waste product, could be very useful in the bioremediation of environments contaminated with pyrene